This invention relates to a method for imparting soil-resistant and water-repellent properties to fibrous polyamide substrates (such as carpet fibers) by applying an acidic aqueous treating solution containing a silsesquioxane. This invention also relates to the treating solution used to impart soil resistance, and water repellency to the fibrous substrate. This invention also relates to treated fibrous substrate made according to the method of this invention.
U.S. Pat. No. 3,493,424 (Mohrlok et al.) describes fibrous materials which are given antislip, dulling, and/or dry-soiling resistance properties by applying a colloidal suspension of a silsesquioxane, followed by drying the material.
U.S. Pat. No. 4,351,736 (Steinberger et al.) describes a textile pile-stabilizing impregnating agent comprising a colloidal suspension of silicic acid and organosilsesquioxanes.
U.S. Pat. No. 4,781,844 (Kortmann et al.) describes a textile finishing agent comprising an aqueous colloidal suspension of an organosilsesquioxane-containing sol and an organic polymer resin containing perfluoroalkyl groups which imparts soil resistance.
This invention describes a novel process for applying an aqueous acidic treatment comprising a silsesquioxane to a fibrous substrate; preferably carpet, to produce fibers that are totally and uniformly treated. Surprisingly, it has been discovered that the anti-soiling and repellent properties of the silsesquioxane compositions are enhanced at low pH. None of the treating compositions and methods described in the art discloses a method for treating a fibrous substrate using an acidic composition comprising a silsesquioxane to simultaneously achieve good antisoiling and good stain resistance properties.
Specifically, this invention relates to a method for imparting repellency and soil resistance to a fibrous substrate comprising the steps of:
(a) contacting the fibrous substrate in a way to cause total wetting with aqueous acidic composition comprising a silsesquioxane
(b) treating the fibrous substrate using a combination of a sufficiently high temperature and a sufficient long time to effectively exhaust the treating materials onto the fibrous substrate; and
(c) drying the wet treated substrate.
This invention also describes the resulting treated fibrous substrates that exhibit excellent anti-soiling and repellency performance.
The treating process for applying the aqueous acidic composition comprising silsesquioxane can be either an exhaustion process or a topical process. In the exhaustion process, a fibrous substrate is first treated exhaustively by contacting the entirety of each fiber of the substrate with the aqueous composition of this invention. Following the contacting step, the resulting totally wet fibrous substrate is then heated in a water-saturated atmosphere such as a steam box for a time sufficient to affix the treating composition onto each fiber surface. The heated wet fibrous substrate is subsequently rinsed with water and is dried in an oven at sufficient temperature to effectively activate the treating composition on the surface of each fiber. In some cases, application at a sufficient high bath temperature (e.g., over 200xc2x0 F. (83xc2x0 C.)) can eliminate the need for the post-steaming operation. The fibrous substrate, having had total penetration throughout each fiber, exhibits significant protection again soiling when compared to untreated carpet as demonstrated by several cycles of xe2x80x9cwalk-onxe2x80x9d tests, and exhibits excellent dynamic water resistance (i.e., the treated carpet resists penetration by water-based drinks spilled from a height).
Examples of suitable exhaustion processes for treating fibrous substrates include immersion, flooding, Beck vat processing, hot otting, padding and puddle foaming application. Useful treating equipment includes equipment available from Eduard Kusters Maschinefabrik GmbH and Co. KG, Krefeld, Germany, such as Kuster""s Flex-nip(trademark) equipment, Kuster""s foam applicator, Fluicon(trademark) flood applicator and Fluidye(trademark) unit.
Suitable topical treating processes for applying the aqueous acidic composition comprising silsesquioxane include spraying and low density foam application. However, exhaustion treating processes are preferred as they impart superior performance to the treated fibers.
To impart antisoiling resistance to the fibrous substrates, the treating compositions of this invention contain silsesquioxanes. Useful silsesquioxanes include compounds of the formula RSiO3/2 where R is an optionally substituted alkyl or aryl of up to 7 carbon atoms, and/or co-condensates of hydrosylates of tetraalkoxysilanes with organotrialkoxysilanes having RSiO3/2 or SiO2 units. Useful silsesquioxanes are described in U.S. Pat. Nos. 3,493,424, 4,351,736 and 4,781,844, each incorporated herein by reference. Preferred silsesquioxanes are neutral or anionic silsesquioxanes, prior to addition to the composition.
Suitable fibrous substrates includes carpet, fabric, textiles and any substrate woven from fibers such as yarn or thread; carpet is the preferred form of the fibrous substrate. The fiber can be made from any number of thermoset or thermoplastic polymers, such as polyamide, polyester, acrylic and polyolefin; polyamide (e.g. nylon) is the preferred fiber.
The silsesquioxane materials can be any of the types described in U.S. Pat. No. 4,781,844 (Kortmann, et al), U.S. Pat. No. 4,351,736 (Steinberger et al.), U.S. Pat. No. 5,073, 442 (Knowlton et al.) or U.S. Pat. No. 3,493,424 (Mohrlok et al.) each of which are incorporated herein by reference. These silsesquioxanes are of the formula Rxe2x80x94Si(ORxe2x80x2)3 alone or together with silanes of the formula Si(ORxe2x80x2)4 wherein R represents a substituted or unsubstituted hydrocarbon radical having 1 to 7 carbon atoms, substituents of which may be halogen atoms and amino, mercapto and epoxy groups, and up to 95% of the R radicals may be methyl groups. Rxe2x80x2 represents an alkyl radical with 1 to 4 carbon atoms. Preferred silsesquioxanes are those that are neutral or anionic.
The silsesquioxanes may be prepared by adding silanes to a mixture of water, a buffer, a surface active agent and optionally an organic solvent, while agitating the mixture under acidic or basic conditions. It is preferable to add the quantity of silane uniformly and slowly in order to achieve a narrow particle size of 200 to 500 Angstroms. The exact amount of silane which can be added depends on the substituent R and whether an anionic or cationic surface active agent is used.
Copolymers of the silsesquioxanes in which the units can be present in block or random distribution are formed by the simultaneous hydrolysis of the silanes. The preferred amount of silane of the formula Si(ORxe2x80x2)4 added is about 2 to 50 percent, relative to the total weight of the silanes employed, prefereably 3 to 20 percent.
The following silanes are useful in preparing the silsesquioxanes of the present invention: methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxyoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, 2-ethylbutyltriethoxysilane, tetraethoxysilane, and 2-ethylbutoxytriethoxysilane.
Generally the composition of this invention comprises from about 0.01 to 1.0 grams of silsesquioxane (0.0025 to 0.25 wt %) dissolved or dispersed in 400 g of water. This composition may be used to exhaustively treat about 100 g of carpet. Preferably the composition comprises from about 0.05 to 0.5 grams of silsesquioxane. The aqueous composition may be rendered acidic by the addition of any inorganic or organic acid, with inorganic acids such as sulfuric being preferred. The acidic aqueous composition preferably has a pH of 4 or less, and more preferably 2 or less.